New Comet Photos Show Icy Target for NASA Probe

This visitor from deep space, seen here by NASA's Wide-field Infrared Survey Explorer, or WISE, is comet Hartley 2 — the destination for NASA's EPOXI mission. This image was taken May 10, 2010 and released Oct. 5.Credit: NASA/JPL-Caltech/UCLA [Full Story]

New photos
of an icy comet taken from Earth and space are giving astronomers a tantalizing
preview of the object ahead of an upcoming flyby of a NASA spacecraft.

In one
photo, the Comet Hartley 2 is shown as it appeared to the camera eye of NASA's
Wide-field Infrared Survey Explorer ? or WISE ? a space telescope scanning the
solar system for hidden asteroids and comets. Another snapshot, taken by a NASA
scientist using an Earth-based telescope, shows the comet as little more than a
bright green smudge against the black background of space. [New Photo of Comet
Hartley 2]

Even the
Hubble Space Telescope has taken a gander at Hartley 2, revealing it as a bright comet sailing in a sea of night. The comet is nearly 1 mile (1.5 km)
wide, according to the Hubble observations.

The new
photos set the stage for the planned Nov. 4 flyby of Comet
Hartley 2 by NASA's Deep Impact spacecraft, a probe that completed its main
mission to a different comet in 2005 and is being recycled to visit Hartley 2
as part of a new project called Epoxi.

"We
want to know how the comet behaves as it comes toward the sun and out of deep
freeze," said James Bauer, a scientist at NASA's Jet Propulsion Laboratory
in Pasadena, Calif., working on the WISE mission. "The WISE image is one
critical puzzle piece of many that will give a comprehensive view of the
behavior of the comet through the time of the encounter." [WISE Telescope Image
of Comet Hartley 2]

NASA
scientist William Cooke took the new ground-based photo of Comet Hartley 2.
Cooke used a telescope near Mayhill, N.M, which he controlled via the Internet
from his home in Huntsville, Ala.

"Comet-watching
from the comfort of your living room!" NASA officials wrote in a blog.
"Modern astronomy is truly amazing."

Green
comet approaches Earth

Comet
Hartley 2, also known as 103P/Hartley 2, is a small periodic comet. It was
first spotted by Australian astronomer Malcolm Hartley in 1986 and orbits the
sun once every 6.5 years.

This year, the
comet will make its closest approach to Earth since it was first discovered. On
Oct. 20 it will come within 11 million miles (17.7 million km) of Earth.

The WISE
photo of Comet Hartley 2 was taken on May 10, but released today (Oct. 5). The
comet has been displaying an increasing amount of activity in recent months,
with gas and dust erupting from jets as it draws closer to the sun.

"Comparing
the dust early on to what we see later with Epoxi helps us understand how the
activity started on Hartley 2," said Epoxi mission principal investigator
Michael A'Hearn of at the University of Maryland in College Park.

But the
observations from Hubble found no evidence of the types of outgassing jets
typically seen in the so-called "Jupiter family" of comets, a group
that includes Hartley 2. Instead, the comet appears to have a more uniform
nucleus, suggesting that the material on its surface is relatively young, researchers
said.